Are bio-based plastics the answer?
By University of Plymouth
Such materials are increasingly being advocated as
environmentally friendly alternatives to plastics, and used in textiles and
products including clothing, wet wipes, and period products.
However, microfibres of the materials are emitted into the
environment through the laundry cycle, the application of sewage sludge as
fertilizers, or the simple wear and tear of textile products.
Despite increasing quantities of bio-based products being
produced and sold all over the world, there has been little research to assess
their potential impact on species and ecosystems.
To address that, a new study in the journal Environmental
Science and Technology tested the effects of conventional polyester
fibers and two bio-based fibers –viscose and lyocell – on earthworms, a species
critical to the health of soils globally.
The study found that in high concentrations of fibers, 30%
of earthworms died after 72 hours when exposed to polyester, while those
exposed to the bio-based fibers experienced much higher mortality of up to 60%
in the case of lyocell and 80% for viscose.
Long-Term Effects on Earthworm Reproduction and Growth
A second experiment, using environmentally relevant
concentrations of the fibers, indicated that earthworms housed in soils
containing viscose fibers exhibited reduced reproduction compared to those
exposed to polyester fibers. Earthworms in the soils containing lyocell fibers
showed reduced growth and also higher rates of burrowing within the soil
compared to exposure to the other types of fiber.
The researchers say the study highlights the complex nature
of global efforts to reduce the threat of microplastic pollution, and the
importance of testing new materials being advocated as alternatives to plastics
before they are released on the open market.
The study was carried out as part of the BIO-PLASTIC-RISK
project, led by researchers at the University of Plymouth and the University of
Bath, and supported with £ 2.6 million funding by the Natural Environmental
Research Council.
Calls for Further Research and Regulatory Oversight
Dr Winnie Courtene-Jones, lead author on the new study and
now a Lecturer in Marine Pollution at Bangor University, said: “Over 320,000
tonnes of bio-based and biodegradable fibers were produced globally in 2022 and
research shows that substantial quantities of that will end up in the
environment. However, evidence of their ecological impacts has been lacking.
Our study has shown that bio-based fibers have a range of adverse effects on
earthworms – animals which are critical to the functioning of the environment.
It highlights the importance of gathering further evidence before alternatives
to conventional plastics are made available even more widely.”
The new study follows research published earlier in 2024
which highlighted that being exposed to the materials used in biodegradable
teabags can result in earthworm populations experiencing up to 15% greater
mortality, and have a detrimental effect on earthworm reproduction.
It has been published just a few weeks before the United
Nations gathers world leaders meet in Busan, South Korea, for the final round
of negotiations regarding a possible Global Plastics Treaty.
Professor Richard Thompson OBE FRS, senior author on the new
study and Head of the University of Plymouth’s International Marine Litter
Research Unit, will be at those discussions along with policymakers,
scientists, and other delegates from across the world.
He added: “It is clear that along with recycling and re-use,
tackling plastic pollution will require a reduction in the quantities of
plastics used and produced. There is increasing interest in alternative
materials that could be used as substitutes for plastic, but this publication
further emphasizes the importance of testing new innovations in relevant
environmental settings prior to widescale adoption. I firmly believe it is
possible to tackle the plastic pollution crisis, but independent scientific evidence
will be critical in helping us avoid unintended consequences as we look for
solutions.”
Reference: “Are Biobased Microfibers Less Harmful than
Conventional Plastic Microfibers: Evidence from Earthworms” by W.
Courtene-Jones, F. De Falco, F. Burgevin, R. D. Handy and R. C. Thompson, 5
November 2024, Environmental Science & Technology.
DOI: 10.1021/acs.est.4c05856
